The invention relates to a device for writing information blocks in a track pattern on a record carrier of a rewritable type, which device is provided with a writing unit for writing areas of the record carrier via (i.e. by using) a beam of electromagnetic radiation with marks representing the information blocks, and positioning means for positioning the writing unit based on a track structure which defines a track pattern on the record carrier.
The invention also relates to a method of writing information blocks in a track pattern on a record carrier of the rewritable type. Marks representing the information blocks are written in areas of the record carrier via a writing unit via a beam of electromagnetic radiation. The writing unit is positioned on the basis of a track structure which defines the track pattern.
The invention further relates to a record carrier for use in the writing device.
Moreover, the invention relates to a reading device for reading information blocks represented by optically readable marks in a track pattern on a record carrier. The device is provided with a reading unit for reading the marks via a beam of electromagnetic radiation, and apparatus for positioning the reading unit on the basis of the marks.
A writing device, a method and a record carrier of the type described in the opening paragraph for writing information blocks are known from U.S. Pat. No. 4,901,300 (PHN 12.398). In the system described in that document, information blocks are recorded in a track pattern on the record carrier and represented by optically readable marks. The record carrier has a track structure in the form of a wobbling pregroove having a varying frequency which represents position information. The writing device has a write head for scanning the record carrier via a beam of electromagnetic radiation. The tracking signals are derived from reflected radiation. The writing device includes for positioning the write head during scanning based on the position information. During scanning, the wobble causes a modulation in the tracking signals. This modulation comprises the position information coded therein, which indicates the absolute position in the track with respect to the starting point of the area intended for information. The information blocks are recorded on the record carrier at a desired position in conformity with their address, while the write head is positioned, if necessary via a jump to another radial position in the track, on the basis of the position information. A record carrier may have been partly written and then includes written areas in which marks are present, and non-written areas in which only the track structure is present. There are reading devices which derive the tracking signals and/or position information from the marks.